Bond fixture for root end laminate or rotor blade

ABSTRACT

A bond assembly includes a fixture having a first section movably coupled to a second section. The first section and the second section are disposed opposite one another. A bladder assembly is mounted to at least one of the first section and the second section. The bladder assembly is configured to apply controlled, localized pressure and heat to a component receivable between the first section and the second section.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority to U.S. application Ser. No.15/232,265, filed Aug. 9, 2016, the contents of which are incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein generally relates to a rotor bladeof a rotary-wing aircraft, and more particularly, to a system and methodfor bonding a laminate of a rotor blade.

Various components, such as a rotor blade of a rotary wing aircraft forexample, have a plurality of holes grouped together in a hole pattern.Although the hole pattern on each rotor blade is substantiallyidentical, the position of one or more of the holes of the pattern mayvary slightly between rotor blades due to the allowable tolerances. Insome instances, a component is mounted to the surface of the rotor bladeadjacent the hole pattern. As a result, the hole pattern must be formedin both the component and the rotor blade.

During initial manufacturing of the rotor blade, the hole pattern may beformed in the component and the rotor blade simultaneously such thatalignment between the component and the rotor blade is not an issue.However, over time, the component may wear and eventually needreplacing. The hole pattern of the replacement component must maintainconcentricity with the existing hole pattern of the blade when thereplacement component is bonded thereto.

BRIEF DESCRIPTION OF THE INVENTION

According to one embodiment of the invention, a bond assembly includes afixture having a first section movably coupled to a second section. Thefirst section and the second section are disposed opposite one another.A bladder assembly is mounted to at least one of the first section andthe second section. The bladder assembly is configured to applycontrolled, localized pressure and heat to a component receivablebetween the first section and the second section.

In addition to one or more of the features described above, or as analternative, in further embodiments the bladder assembly includes aheater.

In addition to one or more of the features described above, or as analternative, in further embodiments the heater is mountable to anexterior surface of the component receivable within the bond assembly.

In addition to one or more of the features described above, or as analternative, in further embodiments the heater includes a plurality ofregions and a heat output from each of the plurality of regions issubstantially identical.

In addition to one or more of the features described above, or as analternative, in further embodiments the heater includes a plurality ofregions and a heat output from at least one of the plurality of regionsis different.

In addition to one or more of the features described above, or as analternative, in further embodiments comprising a rigid caul platepositioned between the bladder assembly and the adjacent surface.

In addition to one or more of the features described above, or as analternative, in further embodiments the first section and the secondsection are coupled by at least one threaded fastener and rotation ofthe at least one threaded fastener about an axis causes the firstsection to move relative to the second section.

In addition to one or more of the features described above, or as analternative, in further embodiments comprising a second fixture,separated from the fixture by a distance.

In addition to one or more of the features described above, or as analternative, in further embodiments a position of the second fixture isadjustable relative to the fixture.

In addition to one or more of the features described above, or as analternative, in further embodiments the component is a rotor blade.

According to another embodiment, a method of bonding a laminate to arotor blade includes installing the laminate about a surface of therotor blade and positioning the rotor blade within a fixture. The rotorblade is secured within the fixture and one or more bond cyclesincluding applying localized and controlled heat and pressure to thelaminate are performed via the fixture.

In addition to one or more of the features described above, or as analternative, in further embodiments the fixture includes a first fixtureand a second fixture and the method further comprises adjusting arelative position between the first fixture and the second fixture.

In addition to one or more of the features described above, or as analternative, in further embodiments comprising installing a caul platein overlapping arrangement with the laminate.

In addition to one or more of the features described above, or as analternative, in further embodiments securing the rotor blade within thefixture includes moving a first section of the fixture relative to asecond section of the fixture to position at least one bladder assemblyin contact with the rotor blade.

In addition to one or more of the features described above, or as analternative, in further embodiments comprising connecting a power supplyto the fixture to apply heat to the laminate.

In addition to one or more of the features described above, or as analternative, in further embodiments comprising connecting an air supplyto the fixture to apply controlled pressure to the laminate.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of an example of a rotary wing aircraft;

FIG. 2 is a perspective view of a laminate of a rotor blade of a rotarywing aircraft;

FIG. 3 is a perspective view of a bonding assembly for bonding alaminate to a rotor blade according to an embodiment;

FIGS. 4a and 4b are various views of the bonding assembly for bonding alaminate to a rotor blade according to an embodiment;

FIG. 5 is a perspective view of a first fixture of the bonding assemblyaccording to an embodiment;

FIG. 6 is a perspective view of a support block assembly according to anembodiment

FIG. 7 is an root end view of a the rotor blade positioned within thebonding assembly according got an embodiment;

FIG. 8 is a perspective view of a nesting assembly according to anembodiment; and

FIG. 9 is a method of using the bonding assembly to bond a laminate to arotor blade according to an embodiment.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 schematically illustrates a rotary-wing aircraft 10 having a mainrotor system 12. The aircraft 10 includes an airframe 14 having anextending tail 16 which mounts a tail rotor system 18, such as ananti-torque system for example. The main rotor assembly 12 is drivenabout an axis of rotation A through a main gearbox (illustratedschematically at T) by one or more engines E. The main rotor system 12includes a plurality of rotor blade assemblies 20 mounted to a rotor hubassembly H. Although a particular helicopter configuration isillustrated and described in the disclosed non-limiting embodiment,other configurations and/or machines, such as high speed compoundrotary-wing aircraft with supplemental translational thrust systems,dual contra-rotating, coaxial rotor system aircraft, turbo-props,tilt-rotors, and tilt-wing aircraft are also within the scope of theinvention.

An example of a laminate 24, typically mounted at a root end 22 of arotor blade assembly is illustrated in FIG. 2. A plurality of holes 26formed in the laminate 24 is configured to align with correspondingopenings (not shown) formed in the rotor blade 20. A plurality ofalignment pins 27 arranged within the holes 26 act as tool to positionthe laminate relative to the rotor blade 20.

With reference now to FIGS. 3-8, an example of a bonding assembly 30 forbonding the laminate 24 to the rotor blade 20 such that the holes 26 ofthe laminate 24 are properly aligned with the rotor blade 20 isillustrated. As shown, the bond assembly 30 includes a table 40 having aplurality of feet 42 configured to rest on or couple to a floor with oneor more fasteners (not shown). An upper surface 44 of the table 40 isarranged generally level to the floor, such as at an ergonomic heightfor example.

A first fixture 50 is attached to the table 40 and is configured toreceive the root end 22 of the rotor blade 20 therein. In theillustrated, non-limiting embodiment of FIG. 3, the bonding assembly 30additionally includes a tip end fixture 52, separated from the firstfixture 50 by a distance, and configured to receive a portion of therotor blade 20, such as an outboard end 28 thereof, near the blade tipfor example. A contour of the second fixture 52 is generallycomplementary to the portion of the rotor blade 20 received therein. Inaddition, one or both of the fixtures 50, 52 may be configured totelescope about a vertical axis, such that the rotor blade 20 isgenerally rotatable about an axis disposed at the inboard end thereof.It is understood that, in other aspects, other numbers of fixtures couldbe used according to the need to support the rotor blade

As best shown in FIG. 8, a nesting assembly 54 having one or morecontours complementary to the rotor blade 20 is configured to at leastpartially support the rotor blade 20 when mounted in the assembly 54.The nesting assembly 54 is positioned between the first fixture 50 andthe second fixture 52 and may include two corresponding halves 56, 58configured to clamp about the rotor blade 20. Alternatively, or inaddition, a leading edge support 60, similar to the second fixture, andhaving a contour complementary to the leading edge 29 of the rotor blade20, may be mounted to the table 40 for the rotor blade 20 to restthereon.

The first fixture 50 is illustrated in more detail in FIGS. 6 and 7. Thefixture 50 is generally equal in length to the root end 22 and includesa first section 62 and a second section 64 configured to cooperate in amanner similar to a vice. The first section 62 and the second section 64are connected by one or more threaded fasteners 66. The first section 62is movably mounted to the table 40 such that as the threaded fasteners66 are rotated, the spacing between the first and second sections 62, 64is adjusted.

Extending from the first section 62 of the first fixture 50 is at leastone first bladder assembly 70 configured to apply pressure to a firstsurface of the rotor blade 20 and extending from the second section 64of the fixture 50 is at least one second bladder assembly 72 configuredto apply pressure to a second, opposite surface of the rotor blade 20.In embodiments including a plurality of bladder assemblies 70, 72extending from a single frame section 62, 64, the plurality to bladderassemblies 70, 72 may be operably coupled or may be independentlyoperated. The portion of the bladder assemblies 70, 72 arranged incontact with the rotor blade 20 may be formed from any suitable materialthat does not damage the surface of the rotor blade 20 when applyingpressure thereto. In an embodiment, the bladder assemblies 70, 72 have acontour complementary to a corresponding surface of the blade 20 toapply a uniform pressure thereto.

In an embodiment, the surfaces of the bladders 70, 72 configured toapply a pressure to the rotor blade 20 include a multi-zoned heaterblanket or other heating element 74 for applying a heat to the rotorblade 20 during the curing process. Depending on the construction of theheater blanket 74, the heat output from the heater blanket 74 may beconstant, or may vary across at least one of the span and the chord ofthe rotor blade 20. In addition, a contour plate (not shown) generallycomplementary to the laminate 24, such as a caul plate formed from athin aluminum material for example, may be positioned between eachbladder 70, 72 and the laminate 24 to evenly distribute the heat andpressure applied to the rotor blade 20 via the bladders 70, 72. Inaddition, a material, such as rubber for example, may be positionedabout a periphery of the caul plates to provide additional contactpressure in the thin composite regions of laminate 24-.

In an embodiment, a support block assembly 76, shown in FIG. 6, isconfigured to mount to an edge of the laminate 24 at the inboard end 36of the rotor blade 20. A portion of the support block assembly 76 has acontour corresponding to an adjacent portion of the laminate 24. Inaddition, the support block assembly 76, may include a handle 78 toallow a user to easily manipulate and position the support blockassembly 76 relative to the rotor blade 20. In addition, the supportblock assembly 76 may include an alignment feature (not shown), such asa tab that connects to the interior surface at the root end 36 of therotor blade 20, within the blade spar 38 for example. The alignmentfeature is configured to associate the support block assembly 76 withthe rotor blade 20 and maintain the laminate 24 in the correct positionduring installation within the assembly 30.

A method 100 of bonding a laminate 24 to a rotor blade 20, shown in FIG.9, includes adjusting a position of the second fixture 52 relative tothe first fixture 50 in block 102. In an embodiment, the position of thesecond fixture 52 is measured using a laser level positioned on thetable 40 supporting the first fixture 50, as shown in FIGS. 4a and 4b .In block 104, the laminate 24 is positioned adjacent the rotor blade,and a plurality of alignment pins 27 are inserted into the alignmentholes 26 formed in the laminate 24 and a caul plate is installed overthe laminate 24. Inclusion of the alignment pins 27 prevents adhesivefrom entering into the alignment holes 26. In an embodiment, thealignments pins have a feature formed on the end thereof, such as astandard square drive for example. Incorporation of the feature makesthe pins compatible with a ratchet making the application of torqueand/or removal of the pins after the bonding of the laminate 24 easierto perform.

In an embodiment the entire bond area may be covered with a sheet ofTeflon® or another suitable plastic material to protect the assemblyfrom adhesive material contacting the fixture surfaces (heaters andbladders). In block 106, the rotor blade 20 is loaded into the assembly,specifically into the first fixture 50 and the second fixture 52 withthe leading edge 29 of the rotor blade 20 facing downwards. In block108, the support block assembly 76 is positioned at the inboard end 36of the rotor blade 20 such that the alignment feature thereof isinserted into the inner mold line of a cavity formed in the blade spar38. The blade 20 is then secured within the first fixture, as shown inblock 110, by tightening together the first and second portions suchthat they clamp around the body. In block 112, a power and an air supplyare connected to the first fixture. A universal controller operates theheater blanket and the bladders to simultaneously apply pressure andheat to the laminate 24, as shown in block 114. After one or morebonding cycles are complete, the air is removed from the bladders andthe bond fixture is removed from the rotor blade, such as in a reverseorder as previously described.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. A method of bonding a laminate to a rotor bladecomprising: installing the laminate about a surface of the rotor blade;positioning the rotor blade within a fixture; securing the rotor bladewithin the fixture; and performing one or more bond cycles includingapplying localized and controlled heat and pressure to the laminate viathe fixture.
 2. The method according to claim 1, wherein the fixtureincludes a first fixture and a second fixture, the method furthercomprising adjusting a relative position between the first fixture andthe second fixture.
 3. The method according to claim 1, furthercomprising installing a caul plate in overlapping arrangement with thelaminate.
 4. The method according to claim 1, wherein securing the rotorblade within the fixture includes moving a first section of the fixturerelative to a second section of the fixture to position at least onebladder assembly in contact with the rotor blade.
 5. The methodaccording to claim 1, further comprising connecting a power supply tothe fixture to apply heat to the laminate.
 6. The method according toclaim 1, further comprising connecting an air supply to the fixture toapply controlled pressure to the laminate.